The idea of Principal Celestia and other characters being teachers intrigues me.
Principal Celestia
Vice Principal Luna
Student President Cadance
Chrysalis is in charge of Biology
Discord in charge of Art and/or Philosophy
Show will almost certainly suck, but I'll have fun riffing on it. Thankfully it looks like a spin off and wont have any impact on S4.
S4 should be interesting. Season 3 seems to have been made with the idea that it was the last season. 65 episodes for a cartoon is common, and I really do wonder if a year or so ago when in production, they thought that would be it. We know they're back for S4, and it will be interesting to see how they recover from their planned ending.